Regulation of precipitant in production of artificial thread



June 30, 1936. HOFMANN 7 7 2,045,598

REGULATION OF PRECI PITANT INTRODUCTION OF ARTIFICIAL THREAD Original Filed March 4, 1950 41/11,, VIIIIIIIIIIIIIIIIIIIQ INVENTOR l'luao HOFMANN BY WKM ATTORNEY Patented June 30, 1936 UNITED STATES PATENT OFFICE REGULATION OF PRECIPITANT IN PRO- DUCTION OF ARTIFICIAL THREAD Application March 4, 1930, Serial No. 433,033 Renewed December 4, 1931 5 Claims.

This invention relates to an improvement in the method and apparatus employed in the precipitation of artificial silk and is concerned more particularly with the provision of means for regulating the flow of the precipitant through the spinning apparatus.

In the production of artificial silk, according to a process such as the cuprammonium stretchspinning process, it is important that the quantity of precipitating liquid flowing in contact with the spinning solution as it emerges from the spraying nozzle be maintained constant, since this liquid accomplishes the initial precipitation and stretching of the filaments leaving the spraying nozzle.

It has been the custom to regulate the flow of liquid to the several spinnerets by using a common supply tank for the precipitant and conducting the precipitant from this supply tank to each of the spinnerets through individual pipes of even diameter, which pipes may include regulating cocks, if further regulation is required. The discharge pipes from the several spinnerets are usually carefully calibrated to permit the uniform discharge of the precipitating liquid from the spinning nozzle. However, in the operation of this process, there is a gradual accumulation of deposited copper hydrate and dirt within these calibrated discharge pipes with the result that the effective diameter of the outlet is reduced and the flow of liquid through the spinneret is decreased.

It is an object of my invention to avoid the above difiiculty and to provide a device which will permit the passage of a substantially uniform quantity of precipitating liquid through each of the several spinnerets. It is a further object of the invention to provide an automatic indicating means to show when any of the individual discharge pipes has become clogged to such an extent that it should be cleaned. Other objects will become apparent.

In describing my invention, reference will be made to the drawing in which the figure represents a sectional view through the supply tanks with one of the spinning nozzles shown in section.

Of the several numerals appearing upon the drawing, la. to le denote a series of spinning funnels of similar construction and 2 represents a common supply tank for supplying the precipitating liquid for use in all of the spinning funnels; 3 represents an intermediate supply tank separated into sections 3a, 3b, 3c, 3d and 3e, and 4a, 4b, 4c, 4d and 4e represent individual calibrated supply pipes leading from the common supply tank 2 to the several compartments of the intermediate supply tank 3. The several compartments of the intermediate supply tank 3 are each connected with one of the spinning nozzles by means of a conduit designated 5a to 56.

The solution to be precipitated is fed to the funnels through conduits 6a to 6e and is forced through numerous small holes in spray nozzles indicated at I. The several filaments from the I) spray nozzles pass with the precipitating liquid through the funnels 8a to Be and the calibrated discharge pipes 9a. to 96, where they are drawn off as the thread l3.

The supply tank 2 is provided with an inlet pipe ID for the precipitating liquid and an over flow pipe ll. Each of the compartments of the intermediate tank 3 has an outlet, lZa to lZe, through which the precipitating liquid will over flow when it reaches the level of the outlet.

In operating my improved device, the precipitating liquid is allowed to enter the tank 2 through the pipe in at such a rate that a slight excess will continuously overflow through the pipe II. The several calibrated pipes, 4a. to 4c, supply the precipitant to the several compartments, 3a to 3e, of the intermediate tank 3 and the liquid from each of these compartments is led to a corresponding spinneret where it comes in contact with the liquid extruded from the nozzle 1 and passes with it through a funnel 8 and a discharge pipe 9.

When the discharge pipes are clean and will permit a full stream to be discharged therethrough, the level of liquid within the inter- 35 mediate supply tank 3 will be at its minimum, as indicated in compartments 3a and 311. As the discharge pipe becomes filled by the slow accumulation of deposit, the level of the precipitant in the corresponding compartment of the intermediate supply tank will rise as indicated in compartments 3b, 3c and 36. When the level of the liquid in any of the compartments of the intermediate supply tank reaches the level of an overflow l2, the excess liquid will run out through the overflow and will indicate to the operator that the congestion in the corresponding discharge pipe is such that it should be cleaned out.

The increase in the head of liquid in each of the several compartments of the intermediate supply tank, as the deposit increases in the corresponding discharge pipe, will compensate to some extent for the reduction in flow of the liquid due to such restriction, with the result that substan- 55 tially the same quantity of precipitating liquid will flow through the spinneret.

The quantity of precipitant supplied to each of the compartments of the intermediate supply tank will be substantially constant since the head of liquid in tank 2 is maintained constant. There will be a slight variation in the difierential head due to the change of level in the separate compartments 3a to 3e, but this difference will be small as compared to the total difierential head. This flow may be maintained more constant by terminating the pipes 4a to 46 above the maximum level of the liquid in the compartments, if such operation is deemed advisable.

Although the rate of flow of the liquid discharged through the outlet pipes 9a to 96 will increase as the head of liquid in the corresponding intermediate supply compartment increases, the effect of this difference will be of no great importance, since the filaments are drawn from the outlet at a rate-greater than their speed within the spinneret. Furthermore, the indicator outlets l2a to I26 may be positioned at such a height that a negligible difference in speed will result before it is indicated that the discharge pipe should be replaced.

By following my improved procedure a thread of uniform denier may be produced and the operation may be controlled to prevent excessive clogging of the discharge pipes from the spinning funnels.

Although only a single embodiment of my invention has been described, it is apparent that many other modifications might be adopted and it is not intended to hereby limit the invention to the particular arrangement disclosed.

What I claim is:

1. An apparatus for producing artificial thread comprising a plurality of spinning funnels and a common source of supply for the precipitating liquid to be used in each, of a separate container positioned between each funnel and the common source and at a greater height than the funnel and adapted to receive the precipitating liquid for that spinning funnel.

2. An apparatus for producing artificial thread comprising the combination with a plurality of spinning funnels and a container for holding precipitating liquid to be used in said funnels, of a. separate compartment positioned between each funnel and said container, said compartments having overflows positioned to indicate when the 10 liquid level reaches the desired maximum.

3. An apparatus for producing artificial thread comprising the combination with a plurality of spinning funnels and a container for supplying precipitating liquid to be used in said funnels, of a separate compartment positioned between each funnel and said container and at a greater height than the funnel and separate calibrated pipes for conveying uniform quantities of liquid from said container to each of said compartments.

4. In a device of the character described, a source of supply for precipitating liquid to be used in each of a plurality of spinning funnels, separate reservoirs intermediate said source and the spinning funnels for supplying liquid to each funnel by gravity, each funnel being supplied with precipitating liquid from a separate reservoir positioned at an elevation higher than that of the spinning funnel.

5. In a device of the character described, a common source of supply for a precipitating liquid to be used in each of a plurality of spinning nozzles, separate reservoirs intermediate said common source and said spinning funnels for supplying precipitating liquid to each of said funnels, said intermediate reservoirs being positioned above the spinning funnels and provided with means for supplying the precipitating liquid to each spinning funnel by gravity flow from a separate reservoir.

HUGO HOFMANN. 

